Improvement in swing-bridges



UNITED STATES PATENT OEEIoE'.'l

HENRY F. SNYDER, OF WILLIAMSIORT, PENNSYLVANIA.

IMPROVEMENT IN SWING-BRIDGES.

Specification forming part of Letters Patent No. 214,530, dated April22, 1879; application iiled December 16, 1878.

To all whom it may "concern:

Be it known that I, HENRY F. SNYDER, of Williamsport, Lycoming county,in the State of Pennsylvania, have invented certain new and usefulImprovements relating to Swing- Bridges, of which the following is aspecication.

My invention is of the class more especially adapted for bridging acrosscanals in cities where the large amount of traffic would render anelevated bridge inconvenient. Such bridges have been constructed to beopened by the force of `the passing boats, and' to be closed again bytheir own gravity, inclines being formed in a circular track, and wheelsbeing provided to run thereon to allow of that mode of operation.

The structure is liable to warp and settle unequally. I mount the wheelson spiderarms which connect to a ring fitting so as to freely turn on axed central post, and I bevel the inner surfaces of the ring, so thatthe ring may be strained into a position considerably oblique to thecentral post, or the post may become inclined, while the ring remainslevel, without binding, while still retaining a close iit. The topcastingis also similarlyfitted. The chances of the central post becominginclined or loosened are reduced by casting it in one with thebed-casting, and by making an upright hollow cylinder of considerablesize, casting it in one with the bed. Itis very reliable.

My invention allows the ways to be imperfectly shaped without involvingany more serious difficulty than the shifting of the bearing outward orinward. The narrow line of the bridge. Fig. 2 is a side elevation. Fig.3 is a top View of the anti-friction rollers and attachments. Fig. 4 isa central section through the spider, showing one arm and roller. Fig. 5is a central -section through the bed-plate and post. Fig. 6 is acentral section of the upper plate. Fig. 7 is a view showing the uppertrack reversed and Fig. 8 is a front view of the pendulum or latch.

Similar letters of reference indicate like parts in all the figures.

A A are the abutments, and a a section of the canal. B is the bed-casting, formed with the stout hollow cylindrical post B in the center, castin one piece therewith, and with the circular track b, also cast in onepiece therewith, and having its upper surface rounded in cross-section,as indicated in Fig. 5.

The spider-frame is `formed witha ring, O1, closely embracing the postB', with liberty to turn around, and also to assume any slightlyinclinedposition required, by reason of the interior of the rin g CI beingbeveled both ways from a narrow bearing, c, at the mid-height, asindicated in Figs. 3 and 4. On the arms C2 are mounted cylindricalbearing-rollers D ofchillcd iron. Y

Eis the uppercasting, having a hole, E',

adapted to receive the large hollow post B.

It has a circular track, e, formed with a rounded bearing-surface castin one therewith, as shown in Fig. 6. One or both of the tracks, b e,are inclined to give the required tendency to the closing motion, aswill be understood. The summit of each incline e1 is formed with a highstop, e2, the two sides of which are curved to the saine radius as therollers. lVhen the bridge is swung to its fullest extent the rollersbear fairly against the stops e2, which arrests its motion.

I propose to employ in addition suitable spring-stops (not represented)in positions at proper distances from the center casting, to be struckby the body of the swinging bridge and aid the stops c2 in arresting themotion.

The bridge M maybe made in any approved manner. It is mounted'stronglyupon the upper casting, E. I have represented it as provided with railsm for a horse-car railroad, which, when the bridge is closed, should bein line with corresponding rails mi m2 of the main track.

It is important to hold the bridge in exactly the right position whenclosed. I have devised a latch which engages very easily and holds thebridge strongly under all ordinary strains; but the piece into which itengages is a lever eounterweighted, so that on the striking of a boat itcan yield and allow the latch to disengage.

G is the latch, (a stout lever,) turning on a center, g, on the underside of the bridge, and guided in a stout keeper, G, which is alsocarried on the bridge, near the working-point of the latch. The engagingpiece is marked H1 H2, the part H2 being much the heavier. It is mountedon a stout pivot, h, and is free to vibrate in a casing or housingprovided. The notch h in the part H1 is adapted to receive the latch G.It maybe slightly beveled. The notch is not V-shaped sufficiently toallow the latch to lift itself out under any lateral force applied. y

The swinging device H1 H2 is of such weight that it holds its place withsuflicient force to resist all the tendencies of the bridge to move inconsequence of wind or the irregular Ino- ,tion received from carriagesand cars. When the bridge swings into the shut position, the latch Gstrikes the rounded surfaces of the part H1 and is lifted. On reachingthe notch h it instantly engages, and after one or two slight rockingmotions of the device H1 H2 the whole comes to rest. The entire bridgeremains thereafter a fixture under all ordinary forces. But the momentthe bridge is, in the working ofthe canal, struck by a rapidlymovingboat, it acts so powerfully on the latch Gr that the device Hl H2 isinstantly tilted in the required position, the force of the boatovercoming the gravity of the heavy part H2, and causing it to swing farenough in the required direction to liberate the latch. rIhusconditioned the latch easily leaves the cavity l1. and the bridge swingsopen.

Modiications may be made. I have represented the castingsB and E asopen-work. They may be made continuous. rIhe spiderframe may be all ofcast-iron, but I prefer that the main portion of the arms be ofwrought-iron. It is important that the center 7b be very stronglysupported; but provision may be made for giving it elasticity, and alsofor adjusting it to a considerable extent up and down'and to the rightand left, as may be required, to cause the latch G to engage properly,and to hold the tracks m mi m2 correctly in line.

Not only the spider -frame C1 C2, but also the upper casting, E, isliable to be twisted into a position more or less oblique to the centerpost, B. I give its interior the same iinish I have described for theinterior of the spider-frame, and for the same purpose.

The cylindrical rollers D are cast in chills. The hardness thus acquiredallows them to endure the slight rubbing action to which they aresubjected in twisting around on the narrow bearing formed by myswelled-face tracks.

The invention may be used for other than canal -bridges, and perhaps insome other structures than bridges strictly so-called, as gates,turn-tables, Src. I use the term bridge to include such.

I claim as my inventionl. In a selfclosing bridge having circular tracksb c and bearing rollers D, the spiderframe C1 C2, having a narrow innerbearing,- c, in combination with a xed central post adapted to both turnand tilt, as herein speciiied.

2. In a canal-bridge adapted to be opened by a blow from a passing boat,the fasteninglatch G and yielding catch H1 H2, adapted to automaticallysecure and :release the bridge, substantially as herein set forth.

In testimony whereof I have hereunto set my hand this 13th day ofDecember, 1878, in the presence of two subscribing witnesses.

HENRY F. SNYDER.

